easeOutBack constant
A cubic animation curve that starts quickly and ends slowly. This curve is similar to Curves.elasticOut in that it overshoots its bounds before reaching its end. Instead of repeated swinging motions after ascending, though, this curve only overshoots once.
Derived from Robert Penner’s easing functions.
Implementation
static const Cubic easeOutBack = Cubic(0.175, 0.885, 0.32, 1.275);